Lone Wolf and Santa FeI believe on Southern Pacific that there are passing sidings, without industrial spurs in the vicinity, which the train enters the siding via the straight track and exits via the turnout.
I have looked at a lot of SP track charts and don't remember any examples of this. At which locations are you seeing this?
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JohnPenn74 1) What I am looking for is at what point in railroad history do we start putting passing sidings down with 2 left switches or 2 right switches where by you enter on the straight leg and leave on the divergent leg. Is it do to restricted speed regulation?
1) What I am looking for is at what point in railroad history do we start putting passing sidings down with 2 left switches or 2 right switches where by you enter on the straight leg and leave on the divergent leg. Is it do to restricted speed regulation?
IF such situations are in fact common, I wonder if it's not something that was done when a railroad's double-track mainlines were been converted to single track, rather than the line being originally built that way long ago. When choosing where to change to single track, putting turnouts where they would make the smoothest transition for trains would probably be a factor.
JohnPenn74Lone Wolf, Why does SP do it this way? Why does Japan do it this way? (In on straight and out on curve. FRA?
In the US (can't speak for Japan), those types of situations would be the exception, not the rule. In the vast majority of cases the main track route will be the highest speed route and the slower speed route through the turnout will be the siding, crossover or the secondary route. I'm sure that somebody can find an exception that was dictated by the physical track arrangement, but in 99.99% of the time the main track route will be through the highest speed route of the turnout, which in the vast majority of the cases would be the straight route.
Dave H. Painted side goes up. My website : wnbranch.com
JohnPenn74 Lone Wolf, Why does SP do it this way? Why does Japan do it this way? (In on straight and out on curve. FRA? JP
Lone Wolf, Why does SP do it this way? Why does Japan do it this way? (In on straight and out on curve. FRA?
JP
"FRA?" So are you asking if this is regulated? In the US such engineering details are not outlined in regulations, only the performance results are set by regulation.
The US history of having hundreds of private railroads rather than a few government railroads means there is a completely different culture in the way regulations are created and administered.
The wide range of operating conditions in the US also means one size diss not fit all.
Sheldon
Take a look at this trackage, double track to triple track transition on the North East Corridor, just south of the Susquehanna River (zoom in on the push pin):
https://www.bing.com/mapspreview?osid=239487e6-18ab-43f0-8560-7555021d8fc3&cp=qkqd688nqztv&lvl=17&style=b&v=2&sV=2&form=S00027
You will notice the tracks are curving, the outer tracks are the mailine, the center track is the "siding". The north side (top right) turnout is basically straight as it goes into the center track, making the mainline the curved part of that turnout.
From point to frog, all three turnouts are between 200 and 250 feet long. The whole crossover is nearly 1000' long.
Trains travel all possible routes at speeds well above 60 mph.
Lone Wolf and Santa FeIn general the mainline does not turn at the turnout.
Unless its taking a diverging route onto a secondary main line.A passing siding is part of the main line at least it was in my 9 1/2 years of railroading.
The dispatcher can run you through a passing track while a track gang is working on the main. Needless to say a lot of horn and constant bell ringing is needed along with restricted speed as per the daily..The dispatcher can have train A to hold the main while train B passes or over takes train A.
Unlike the Santa Fe we stopped on the main to switch a industry since there was no passing siding at every industry..
Larry
Conductor.
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"Stay Alert, Don't get hurt Safety First!"
In Japan, little country stations on less important routes were ALWAYS entered on the tangent leg of the facing point switch, which was always a spring switch. At the far end, they took a right-hand jog through the curved routes of a crossover back onto single track - the spring-loaded switch points slamming with every passing wheel.
So, which of the parallel tracks through the station was the main track? BOTH! One was the UP (toward Tokyo) main, the other was the DOWN (away from Tokyo) main, and each was operated directionally 99.44% of the time. The only exception was that there might be need to switch a car into the station spur, in which case the spring-loaded points were manually aligned for the curved route.
Why the crossovers at both ends of the station? The tangent sides of the switches led to spurs covered with about a foot of gravel ballast - runaway train stoppers.
Don't know if this remains the case, but I see no reason to change it.
Chuck (Modeling Central Japan in September, 1964 - with spring switches at stations)
Once again, John Armstrong to the rescue (maybe). In Track Planning for Realistic Operation, he outlines some options for transitions between signle and dual track, or dual track and triple or even quad track. Various combinations and types of turnouts affect the maximum safe speed to negotiate these junctions and there's a pretty good explanation of this in the inage caption and accompanying text. I don't have one of my copies handy to get the exact page, but I believe it is in the first section. I think it carried over to the newer edition - I have a second edition and a third edition, and some stuff got cut out of the third edition to make room for the section on modern railroading.
--Randy
Modeling the Reading Railroad in the 1950's
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7j43k Sheldon, I understand that with a multiple track main line that trains can be moved all over the place. But the OP seems to be talking about ONE siding. As in: enter. leave. Concerning high speed switches: You twice spoke about high speed switches as if track speed was permitted through both routes. I am not familiar with this. Even with #20 switches, the diverging route is slower than the through route. So calling something a "high speed" switch does not mean (to me) that the diverging route speed limit is THE SAME as the through route. I also believe that works for both directions through the switch. I may be misinformed, though. Ed I still would like examples from the OP. Well, more correctly, his sources.
Sheldon,
I understand that with a multiple track main line that trains can be moved all over the place. But the OP seems to be talking about ONE siding. As in: enter. leave.
Concerning high speed switches: You twice spoke about high speed switches as if track speed was permitted through both routes. I am not familiar with this. Even with #20 switches, the diverging route is slower than the through route. So calling something a "high speed" switch does not mean (to me) that the diverging route speed limit is THE SAME as the through route. I also believe that works for both directions through the switch.
I may be misinformed, though.
Ed
I still would like examples from the OP. Well, more correctly, his sources.
Yes, I prefaced my comments that I am not familiar with current practices in single track territory. The mostly single track ex B&O mailine here is not used by AMTRAK or for any kind of passenger service, it is exclusively freight.
The term high speed switch does not automaticly mean both routes can be taken at the same speed, but it does mean that traditional speed restrictions may not apply.
Many high speed areas today have features like moving point frogs, or power closing frogs allowing turnouts larger than #20, as well as equalateral turnouts making a #20 frog effectively a #40 in terms of diverging curvature.
All of these things allow trains on multi track lines like the NEC to travel through turnouts, even what is considered the diverging route, at relatively high seeds. Not necessarly the 88 MPH mainline max, but not 27 MPH either.
This is all determined individually as Larry has been saying and is in the timetable as to what routes have what speeds.
Example, southbound trains cross the Susquehanna bridge which is two tracks, regardless of which track they are directed to south of the bridge, trains move at nearly the same speeds through the next interlocking where the mainline spreads out to three tracks, then later four tracks. The interlocking was designed for this. I don't know the turnout numbers, or the exact speed restrictions, but from watching them it way faster than any 27 mph, more like 50, 60 mph or more. But they are long and gradual and have no curve past the frog as they shift over to the other track. So the only "curve" is the closure rails, or the 3 degree change in direction of a #20 frog or larger, not as sharp as many of the curves they take at 88 mph.
Ed,High speed switches can be used as crossovers and taken at table table speeds but,in normal passing siding use that diverging approach will slow you down. A diverging clear means you are going to pass/overtake a train standing(stopped) on the main and can maintain time table speeds unless there is a restriction for that switch in the daily or orders from the dispatcher...
However,a diverging clear into a secondary sub division will be govern by the restricted speed on the curve on the secondary.In short even with a high speed switch that curve will slow your speed to the time table speed for that curve..That's why I chuckle at some of the "operation" videos by well meaning modelers on you tube since they fly into the diverging leg of a switch even though the signal aspect is diverging approach...
Think of a high speed switch being a HO # 10 or # 12 switch..
JohnPenn741) Am I correct in my assumption of straight switches on both ends of the siding?
Not sure what you mean by "straight switches". Most switches have a straight side and a diverging side. There are "equilateral" switches that have both sides diverging but most of them are at single to double track or double to triple track locations.
In most cases the straight side of the switch is the main track route since the diverging route is speed restricted.
2) Should there always be and LEFT RIGHT combination or has there been FRA **** legal **** requirement allowing or requiring a left left or right right for relief track entry, higher speeds, etc.
3) When in a relief track for higher volume railroads, which track is the main line?
Don't know what a "relief" track is, must be a regional thing. Its not used on the western railroads.
The main track is whatever the timetable says it is.
7j43k JohnPenn74 Here recently I have had friends tell me that when riding Amtrak they are always entering the siding on the straight and leaving on the curve. I'd sure like to hear more details of this. Perhaps you can ask them EXACTLY where these places are. I'd like to look at them with Google satellite views. Yeah, it seems weird. That's why I'm asking for evidence of it. Ed
JohnPenn74 Here recently I have had friends tell me that when riding Amtrak they are always entering the siding on the straight and leaving on the curve.
Here recently I have had friends tell me that when riding Amtrak they are always entering the siding on the straight and leaving on the curve.
I'd sure like to hear more details of this. Perhaps you can ask them EXACTLY where these places are. I'd like to look at them with Google satellite views.
Yeah, it seems weird. That's why I'm asking for evidence of it.
I can't speak for other aras of the country, but here on the Northeast Corridor, I'm sure it can feel that way to riders as trains move from track to track on the mostly 3 and 4 track mainline from Boston to Washington DC.
For whatever reasons your train may be on track three, and stop for a signal, then proceed through an interlocking on to track two for the next leg of your trip. You where not really on a "siding", you where on a specific track in a multi track corridor, then they needed that train to be on a different track in the sub.
As stated in my earlier post, many of the turnouts on the NEC are high speed, trains move from track to track with little or no speed restrictions in many cases.
There are a few bottle necks, like the bridge over the Susquehanna River between Baltimore and Philly. It is an aging ex swing span, only two tracks, speed restricted. The station on its north shore is the limit of MDOT commuter service, so commuter trains and AMTRAK traffic share the bridge, requiring some trains to wait on the three and four track portions of the mailine north and south of the bridge.
You can call that stopping on a siding if you like, but those three and four tracks continue all the way to Baltimore and Phily respectively.
Entering a passing siding you get a restricted "diverging approach" aspect so,you will enter the siding at restricted speed. At diverging clear you enter at time table speed.
The civil engineers planed switches large enough to handle any size locomotives on the reverse route of the switch including Big Boys and C&O's Alleghenies even if that meant replacing outdated switches that couldn't handle large modern steam engines..
As Seldon ponted out some large locomotives was restricted to certain divisons. The reason varies from the weight of the rail to bridge weight limits.
JohnPenn74 Fellow Railroaders, While working on the club layout a competing discussion has evolved as to how the prototype aligns switches at either end of a passing siding / relief track. Being an old school steam guy I am in the camp that the main is defined by straight legs of the switches on either end of the passing. More appropriately, the mainline requires the straight leg on both ends so the 2-10-2, 2-8-8-4 whatever doesn't get fouled up. Here recently I have had friends tell me that when riding Amtrak they are always entering the siding on the straight and leaving on the curve. I know in England passenger trains are not allowed to take the curve unless the switch has point locks. My questions are thus: 1) Am I correct in my assumption of straight switches on both ends of the siding? 2) Should there always be and LEFT RIGHT combination or has there been FRA **** legal **** requirement allowing or requiring a left left or right right for relief track entry, higher speeds, etc. 3) When in a relief track for higher volume railroads, which track is the main line? JP
Fellow Railroaders,
While working on the club layout a competing discussion has evolved as to how the prototype aligns switches at either end of a passing siding / relief track.
Being an old school steam guy I am in the camp that the main is defined by straight legs of the switches on either end of the passing. More appropriately, the mainline requires the straight leg on both ends so the 2-10-2, 2-8-8-4 whatever doesn't get fouled up. Here recently I have had friends tell me that when riding Amtrak they are always entering the siding on the straight and leaving on the curve. I know in England passenger trains are not allowed to take the curve unless the switch has point locks. My questions are thus:
1) Am I correct in my assumption of straight switches on both ends of the siding?
JP,
In North America, there are no such regulations about trackage design. Railroad civil engineers design trackage based the operating conditions of each line.
Modern North American mainlines often have high speed turnouts that allow high speed travel through both routes. Even in steam days, many routes had large turnouts allowing high speeds on diverging routes.
Not sure what a point lock is, but passenger trains here go through turnout diverging routes all time. Turnouts are controlled and locked by Centralized Traffic Control, and are equally "safe" on either route at the prescribed speeds.
Turnouts cannot be changed once the train enters the signal block that contains the turnout.
Generally, locomotives were not/are not used in areas containing trackage they can not safely navigate, so concerns about locos getting fouled up are generally unfounded.
There is no specific protocol as to which track is the "siding", or relief track as you call it. That is defined by the indvidual railroad for each siding.
Physically, a switch or turnout has a tangent (straight) leg and a curved leg which of course really isn curved at all, it is just a tangent going off in a different direction. The curve is seen when one tries to run the second track parallel to the first.
Logically, a switch (turnout) has a NORMAL position and a REVERSED position. When controlled from the tower the lever is in the normal position and the swithch too is in its normal position. Reverse the lever, and you reverse the switch. The normal rout my well be the diverging route if that is what the logic of the plant calls for. Such as arriving at or leaving a terminal.
Some switches are controlled by an interlocking machine somewhere, and these will have interlocking or HOME signals to protect them at the train movements. Others are controlled locally, and the conductor must climb down to the ground to operate the switch mannually.
Here in the little town of Richardton ND, (pop <600) we have three kinds of such switches.
The ethanol plant has all manual switches, the turn outs from the main line are locked with a switch lock, and the conductor must climb down onto the ground to throw the switches. Once past that switch (and its associated derail device) the remainder of the switches in the plant are manual and unlocked. Look before you move!
The Halliburton sand plant on the other side of town has powered mainline switches, protectd by signals and controled from Ft. Worth TX. Once past these, you again have manual switches, aligned in advance by the plant crews.
The passing siding is signalled from Ft. Worth, but the switches are "semi-automatic", when the signal dictates that the train is to take the siding, the conductor climbs down and throws the switch with a complicated pumping action. He then gets back onto the locomotive and the train enters the siding. Once the train is clear of the switch, it automaticaly returns to the normal position (using the energy that the conductor 'pumped' into the device upopn entering). This allows the train to operate without a caboose or a switchman at the end of the train, and it allows the opposing train to continue through without stopping.
Penn Station in New York City operates differently, but then they must run over 1000 daily trains across the 21 tracks in the station. A movement every 30 seconds.
Track sppeds through the diverging route are controlled by the size of the frog. A number 4 switch would have an 8 mph speed limit. A number 12 switch would have a 24 mph speed limit, a number 20 switch would have a 40 mph speed limit, but any larger than that and you would have to have moving points on the frog as well as at the switch points.
ROAR
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Here there be cats. LIONS with CAMERAS
There is no pat answer. In general, the civil engineers would prefer to design it so that trains on the mainline maintain normal mainline speed. Trains taking siding or reentering the main may be required to reduce speed. The general preference would be for higher speed trains to take the straight leg. However, there is also a school of thought that says a heavy freight train with a very large locomotive should be kept on the mainline to keep it from stopping or going through too many curves and switches. On the prototype, a light passenger train can negotiate such trackage much more easily. In the mountains and in areas of restricted space, it's not unusual to have curved turnouts with no straight leg. It all depends upon the needs of the particular location and the particular operation.
Tom
While working on the club layout a competing discussion has evolved as to WHY the prototype places divergent sides of switches at either end of a passing siding / relief track. Here recently I have had friends tell me that when riding Amtrak they are always entering the siding on the straight and leaving on the curve leg of the switch.
Being an old school steam guy I am in the camp that the main is defined by straight legs of the switches on either end of the passing. This mainline definition is requires the straight leg on both ends so that large rigid wheelbased engines such as 2-10-2, 2-8-8-4 whatever doesn't get fouled up from attempting to take divergent path on a switch that is too small. (IE Northern 8444 will NOT take a divergent path on a #6 switch its just physically too small, the engine will not physcically be able to negotiate it at ANY speed) For this reason, our small siding will have the straight legs on the main and the divergent legs of the turn out on the siding.
I know in England passenger trains are not allowed to take the curve unless the switch has point locks (locks the switch after it is thrown) Explain to me at Severn Valley, 2013.
My questions are thus:
2) when you do have this left left or right right arrangement which track is the main line track? How does dispatch tell the engineer to take the siding, hold the main, etc?
3) Am I correct in my assumption of straight sides of switches on both ends of the siding would define the main in most NORMAL instances?
4) Should there always be and LEFT RIGHT combination or has there been FRA **** legal **** requirement allowing or requiring a left left or right right for relief track entry, higher speeds, etc.
5) When in a relief track for higher volume railroads, which track is the main line?
A "relief track", as I am using the term is a longer, but limited section of double track equipped with high speed switches that permits two opposing trains to pass at higher speed without significant loss of speed or stopping. Passing on the fly as it were. Kalmback, "Track Planning for Realistic Operation"
If you are riding Amtrack from Chicago to Portland, almost every time you stop and pass another train we entered the siding on the straight leg of the switch and left the siding on the divergent leg of the switch. Happened several times along the way.
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